This invention relates to the general technical field of kitchen utensils of the cooking recipient type, and especially to that of pressure cookers, which is to say pressurised cooking pots designed to cook food they contain using pressurised steam.
This invention relates more particularly to a domestic pressure cooker comprising means of controlling at least part of its operation, wherein said control means have a mobile mounting between a plurality of positions.
Domestic pressure cookers are well-known. They are usually composed of a metallic pan designed to accommodate food and a lid, also metallic, designed to be added and locked onto the pan to form with the latter an impervious cooking chamber. Such a pressure cooker is designed to be subjected to the influence of a source of heat (such as for example a cooking hob) so as to permit the increase in pressure and temperature of the chamber and thus the pressurised cooking of the food contained therein.
The operation of these known pressure cookers is controlled by different parts such as for example:                means of locking/release capable of locking and releasing the lid with respect to the pan,        a pressure regulation valve which permits the pressure in the chamber to be maintained at a predetermined level called the operating pressure;        or even a decompression part, permitting the pressure to be lowered in the chamber, especially at the end of the cooking cycle, so that the user may open the lid in acceptably safe conditions.        
Each of these functions may be controlled by the user by one or several corresponding control means designed to be manually actuated by the user.
In particular, a pressurised cooking appliance is known that is equipped with a rotary control knob mounted on its lid, wherein said rotary control knob permits the user to control manually both the locking/release of the lid with respect to the pan and the decompression of the chamber.
More precisely, the rotary control knob has a mobile mounting in rotation between three indexed positions corresponding respectively to specific operating modes of the appliance. Consequently, the rotary knob in question may be placed in a first position called “locked and sealed”, corresponding to the locking of the lid onto the pan and the sealed closure of the chamber so that the latter may increase in pressure. The rotary knob may also be placed in a second position, distinct from the first position, called the “locked and decompression” position. This second position corresponds to the locking of the lid onto the pan as well as bringing the inside of the chamber in communication with the outside to lower the pressure inside the chamber.
Finally, the rotary knob may also be placed in a third position, distinct from the two other positions, called the “opened and released” position, which permits the user to separate the lid from the pan in complete safety, as soon as the pressure inside the chamber drops below a predetermined safety level.
The control knob comprises a handle designed to be turned manually by the user, wherein said handle opens out at its base into a circular crown which is made from the same material as said handle and on which there is a visual positioning identification mark. The control knob is itself attached to a plastic cover with a fixed mounting on the lid, so that the handle and its base turn in relation to the cover.
Pictograms corresponding to the three different positions that the control knob may adopt are present on the cover.
Consequently, for each indexed position of the control knob (position to which a respective operating mode of the pressure cooker corresponds), the visual identification mark on the crown of said knob is located opposite the corresponding pictogram on the fixed cover. In this way, by turning the handle until the identification mark on its crown is aligned with one of the pictograms on the cover, it is possible for the user to select the indexed position (and thus the corresponding operating mode) desired. Reciprocally, the user is able to determine, at all times, by looking at the pictogram opposite the identification mark, in which position the control knob is located and thus which is the specific operating mode currently selected on the pressure cooker.
While such a pressure cooker generally provides full satisfaction, nevertheless it has certain disadvantages.
Consequently, the known pressure cookers compliant with the above description permanently display to the user all of the pictograms of the cover, such that the user is not directly able to determine instantly in which position the control knob is positioned and therefore which operating mode of the pressure cooker is selected. In order to access the desired information, the user is in fact obliged to search, by a positive action, which pictogram is aligned with the identification mark. Therefore quite often, especially for inexperienced users, this observation is not made automatically and consequently the position of the control knob may not correspond to that desired. This lack of ergonomics and clarity of information may lead the user to using the pressure cooker incorrectly (the user thinks for example that a pressurised cooking cycle has been started whereas the pressure cooker has inadvertently been left in the decompression position) or even cause, in the most critical case and combined with other factors, a possible risk of accidents, especially due to burning.
This problem is even more present given that the identification mark on the knob, as the pictograms on the cover, may be relatively difficult to distinguish visually, so that their possible alignment is also difficult to distinguish.
This is due to the fact that for reasons of industrial organisation and durability, the identification mark and the pictograms are generally made by simple forming (hollow or raised) in the component material respectively forming the crown and the cover, without additional colouring.
The identification mark and the pictograms consequently appear in matching tones with respect to the part on which they are marked, which consequently makes them difficult to distinguish, in particular for inexperienced users or those with impaired vision.
Given the relative deficiency of ergonomics and clarity of information related to the visual identification system of the prior art described above, it is necessary for the user to be allowed to view directly the state of certain parts. In particular, it cannot be envisaged, with such a visual identification system, to completely conceal the locking system of the lid onto the pan. On the contrary, for comfort and safety of use, the locking system needs to be kept permanently in view of the user, so that the latter is able to determine precisely if the lid is locked or not onto the pan. However, the fact that the locking system is permanently visible may contribute to what the user may perceive of the pressure cooker as being a complex and dangerous machine, which is not the case.
Similarly, the permanent viewing by the user of all of the pictograms may alter the perception of the user of the degree of difficulty in using the pressure cooker. This degree of difficulty is in fact low or even null, however the multiplication of the visual symbols may allow certain users think that their pressure cooker is a device that is extremely difficult to use and which requires a long and tiresome learning process.